Fluonic control circuit useful with sewing machines



Jan. 16, 1968 R. c. BRANDRIFF ETAL 3,363,595

FLUONIC CONTROL CIRCUIT USEFUL WITH SEWING MACHINES 2 SheetsSheet 1Filed March 8, 1966 wvwVf On mm Witness 1Y09a vwl T4 Jan. 16, 1968 R. c.BRANDRIFF ETAL 3,

FLUONIC CONTROL CIRCUIT USEFUL WITH SEWING MACHINES 2 Sheets-Sheet 2Filed March 8, 1966 lwl m 2 3 5 l l v ON Wiiness [405: L 'u Tfa UnitedStates Patent 3,363,595 FLUONIC CONTROL CIRCUIT USEFUL WITH SEWINGMACHINES Robert C. Branrlriif, Williamstown, and Charles G. Pickett,Dover, N.J., assignors to The Singer Company, New York, N.Y., acorporation of New Jersey Filed Mar. 8, 1966, Ser. No. 532,708 Claims.(Cl. 112-218) This invention relates in general to a fluonic controlcircuit, and in particular to a fluonic circuit for controlling themodulation of a fluid pulse train.

In a presently preferred environment for the invention, the circuit isemployed to monitor the rate of thread consumption of an industrialsewing machine, whereby when such rate is either too low or too high, analarm or other control unit is excited. The circuit of the inventionpreferably-though not necessarily-is adapted to receive a fluid pulsetrain wherein the durations of the pulses therein are all substantiallyconstant, wherein the spacings be tween the pulses of such trainsubstantially constant, and wherein the time-lengths of such durationsand spacings are controllable. When the pulse durations and spacings ofsuch train are substantially equal in time to respective reference timeperiods, the effective output of the instant control circuit is made tobe zero; when such durations and spacings are greater or less in lengthof time than their respective reference time periods, the circuit ismade to produce an output the time integral of which is a signal levelthat is proportional to the departures in length of time of suchdurations, and spacings, from their reference time periods. By providinga detector unit responsive to a predetermined level of the time integralsignal, modulation of the pulse train may be so maintained that theeffective circuit output (and the time integral signal) is always keptdesiriously at zero.

In adapting the circuit of the invention for use as a monitor for therate of thread consumption of an industrial sewing machine, thefollowing factors obtain: A broken needle thread causes the sewingmachine consumption rate thereof to cease, Whereas a broken bobbinthread causes the consumption rate of the needle thread to decrease. Byproviding a pulley having, for example, spokes that are substantiallyequisized with the spacings therebetween, and by directing a thin steadystream of air perpendicular to and at such spokes, a pulse train of airpressure pulses is had if the pulley is rotated by means of theconsumable thread, and if the pulley is of sufficient mass to filter theperiodic demand for thread by the sewing machine. A high rate of needlethread consumption effects pulse durations and spacing that are minimal;a low rate of needle thread consumption effects pulse durations andspacings that are substantial. Hence, by adapting the circuit of theinvention to provide an effective output the time integral of which iszero only when the pulley rotational speed is representative of a sewingmachine that is functioning properly and consuming needle thread at anormal or reference rate, then monitoring of the operation of suchsewing machine, and of its thread consumption, is attained.

In relating the present invention to the prior art, referonce should behad to application Ser. No. 510,227, which is assigned to the instantassignee. As disclosed in such application, the nature of thepulley-produced pulse train required therein is substantially limited toequisized pulse durations and pulse spaces, and further that a pair oftime delay units are needed for circuit tuning purposes. Bothlimitations of the prior art are obviated by the present invention, aswill be described hereinafter.

An object of the invention is to provide a fluonic circuit for use in socontrolling the modulation of a fluid pulse train that the durations ofand the spacings between adjacent pulses thereof are timewisesubstantially equal to respective reference time periods.

Another object of the invention is to provide a fluonic circuitresponsive to produce a control output signal when the durations andspacings of pulses in a received train of fluid pulses are not, inlength of time, the same substantially as respective reference timeperiods.

Another object of the invention is to provide a fluonic circuit forcontrolling the modulation of a train of air pulses.

Another object of the invention is to provide a fluonic circuit for usein monitoring the rotary speed of an element.

Another object of the invention is to provide apparatus for use inmonitoring thread consumption by a sewing machine or similarinstrumentality.

Another object of the invention is to provide apparatus for use inmonitoring the condition of two threads of a sewing machine by sensingthe consumption of only one of said threads.

The invention will be described with reference to the figures wherein:

FIG. 1 is a schematic diagram of a presently preferred embodiment of theinvention,

FIGS. 2A, 2B and 2C are signal diagrams, idealized for instructionalpurposes, which are useful in describing the operation of the circuitdepicted in FIG. 1, and

FIG. 3 is a diagram of an operational curve for the presently preferredembodiment of the invention.

For ease of description, the apparatus of the invention is shown adaptedto employ a fluid pulse train wherein the pulse durations and spacingsare equisized with respect to each other, although as aforesaid this isnot a requirement of the instant apparatus.

Referring to FIG. 1, a sewing machine 10 supports a journal 12 on whicha pulley 14 is rotatably supported. The pulley 14 is provided with aplurality of spokeslfi; and needle thread 318 from the sewing machine 10winds on and drives the pulley 14. To prevent slipping of the thread 18on the pulley, at least a full turn of thread 18 is placed on it, and toguide the thread 18 onto the pulley, thread guides 20, 22 are employed.As above indicated, the pulley spokes 16 are all substantially identicaland are of generally the same configuration as any one spacing 24between adjacent spokes, with the number of spokes in the pulley beingdirectly determinative of the fineness of the control provided by theinstant circuit.

A transmitting tube 26 directs a steady stream of air, provided by asource 28, at the pulley spokes 16 (or spaces 24); and a receiving tube39 is spacially aligned to receive the transmitted air stream when thepulley 14 is so rotated that the transmitting tube 26 aligns with apulley space 24. The transmitting and receiving tubes 26, 30 ideally areso sized that the transmitted air stream is substantially blocked fromthe receiving tube whenever the pulley rotation is such that a spokealigns with the air stream; and the needle thread 18 is disposed on thepulley 14 so as not to interfere with such air stream. Therefore, whenthe pulley 14 is stationary, either a steady air stream, or no airstream, is directed to the receiving tube 30 depending respectively onwhether a space 24 or a spoke 16 aligns with the output of thetransmitting tube 26; when the pulley rotates, a train of air pulses isreceived by the receiving tube 30.

The output of the receiving tube 30, whether a steady air stream or notor Whether a train of air pulses, is

applied to the control port 32 of a monostable (Coanda) fluid amplifier34 that is so biased at 36 that fluid applied to its input 38, atpressure P is normally, i.e. absent fluid signals at .32, directed intothe output leg 40 of the amplifier. With an air pressure signal appliedto the control port 32 of the amplifier 34, however, the input fluid at33 is switched to the output leg 42 of the amplifier.

The control port 44 of .a Coanda flip-flop 46 receives the fluid outputof the leg 40 of the amplifier 34, and serves to switch input fluid, ofpressure P applied at 48 to the output leg 50 of the flip-flop 46. Thefluid pressure signal in the flip-flop leg 50 is applied via anadjustable delay device 52 to the control port 54 of a second Coandaflip-flop 56. The delay device 52, which may take the form for exampleof a needle valve or an adjustable length of tubing, is so adjusted thatthe integrated pressure signal appearing in the output leg 58 of theflip-flop 46 is minimal when the sewing machine 10 is consuming thread18 at its desired normal rate.

Delayed pressure signals applied to the control port 54 of the flip-flop56 switch input fluid, of pressure P applied at 60 to the output leg 62of the flip-flop 56. The fluid output signal of the flip-flop leg 62 isapplied to the control port 64 and serves to switch the pressure P fluidto the flip-flop leg 58. Fluid pressure signals appearing in the leg 42of the amplifier 34 are applied to the control port 66 of the flip-flop56, and serve to switch the pressure P fluid to the flip-flop leg 63,whereby such P fluid is exhausted from the circuitrPressure fluid outputin the leg 58 of the flip-flop 46 is applied to a pressure integratingdetector element 70, e.g. a diaphragm actuator, the output of whichcontrols a detector element which may for example be a microswitch thatexcites an alarm system.

To be noted from FIG. 1 is the fact that the input fluid pressures aresuch that pressure P is less than pressure P and pressure P is less thanpressure P As to operation of the circuit of FIG. 1 for monitoring theconsumption of thread by a sewing machine, the description below relatesto operations under the following conditions: 1) The pulley 14 isstationary, as for example when the sewing machine needle thread 18 hasbroken, and a steady stream of air is transmitted to the receiving tube30 via a pulley space 24. (2) The pulley 14 is stationary, and no airstream reaches the receiving tube, as for example when a pulley spoke 16blocks the air stream. (3) The sewing machine is so functioning nor-.mally that the air pulses produced by means of the pulley are of aparticular duration. (4) The produced air pulses are of longer durationthan such particular duration, as for example when the pulley isrotating at too low a rate in response to, say, a broken bo b binthread. (5) When the pulley is rotating at too high .a rate and theproduced air pulses are of too short a duration.

Condition 1.A steady stream of air from the receiving tube 30, overcomesthe monostable amplifier 34 bias applied at 36, and causes the P fluidto switch to the amplifier output leg 42. Fluid in the output leg 42,absent any P fluid applied at 54, causes the flip-flop 56 to switch andapply its P fluid to its exhaust leg 68. If P fluid is being applied atthis time to the flip-flop leg 58, causing the detector 70 to alarm (forzero thread consumption), it so remains because control signals are atthis time applied to neither control port of the flipflop 46: if at thistime, however, pressure fluid P is being applied to the flip-flop 46output leg 50, it flows via the delay device 52 to override the Ppressure signal applied to the control port 66 because P is greater thanP and causes the P pressure fluid to be applied to the flip-flop 56output leg 62; in turn, the P fluid applied to the control port 64 ofthe flip-flop 46 switches such flipflop to cause the P fluid to flow tothe leg 58 to alarm for zero thread consumption.

Condition 2.-With no pressure applied to the amplifier 34 control port32, the bias at 36 causes the P fluid to flow to the amplifier outputleg 40. This causes control fluid to be applied at 44, and causes theflip-flop 46 to switch its P fluid to its output leg 50. Such P fluid,via the delay device 52, gets applied to the flip-flop 56 control port54, and causes P fluid to be switched to 4 the flip-flop 56 output leg62, thereby applying a control signal to the control port 64 of theflip-flop 46. This causes the flip-flop 46 to switch its P fluid to itsoutput leg 58, whereby the detector 70 alarms for zero threadconsumption.

Condition 3.See in particular FIG. 2A, which shows respective signalwaveforms as they appear at the similarly noted elements of FIG. 1. Withthe delay device 52 properly set, as will be described hereinafter, anda normal pulse train 32 (as produced by a pulley 14 rotating in responseto a sewing machine that is consuming thread at a normal rate) appliedto the input 32 of the amplifier 34, the output legs of the amplifier 34get excited as shown by respective waveform curves 4t), 42. Since theoutput leg 40 of the amplifier 34 alternately is placed under Ppressure, the P fluid is alternately switched to the flip-flop 46 outputleg 50 as shown. Note that the P pressure level, as shown in FIG. 2A, isgreater than the P pressure level. By delaying the P signal waveform,appearing at 50, to coincide phasewise with the P pressure signal at 42(66) the P signal at 66 is repeatedly overridden by the P signal at 54,whereby P pulses are repeatedly applied at 64 to effect P pulses of theflipflop 46 output leg 58. However, since the P pressure pulses appliedat 44 are out of phase with the pulses at 64, the flip-flop 46 leg 50 isexcited as frequently as the leg 58. Because in the instant example, thepulse durations and spacings are equisized, this means that for anormally running pulley, the integrated pressure applied to the detector70 is minimally one-half the P pressure level, i.e. the excitation ofthe flip-flop 46 leg 50 is maximal. By biasing the detector to ignoreintegrated pressures below a certain level P i.e. one-half the Ppressure, and to alarm for integrated pressures above a certainthreshold level P the objects of the invention are attained. See FIG. 3.

Condition 4.See FIG. 2B which shows a series of signal waveforms similarto those shown in FIG. 2A, but indicating that the air pulses producedby a slowly rotating pulley are of longer duration than those producedwhen the pulley is rotating at its normal rate. With long durationpulses applied to switch the monostable amplifier 34, switching signalsare again produced to switch the flip-flops 46 and 56. However, sincethe time delay to the P pressure signal appearing in the output leg 50,as provided by the delay device 52, causes the P signal at 64 to be inphase periodically with the P signal at 44, the P signal periodicallyoverrides the P signal, thereby assuring that the flip-flop 46 leg 53 isexcited for a longer time than the flip-flop 46 leg 50. Integrating theP output pulses in the flip-flop leg 58 produces a steady state pressuresignal above the bias pressure P and which, if greater than thepredetermined pressure threshclfll P etlects actuation of the detectorelement 70. See F 3.

Condition 5.In the case where the pulley 14 is rotating at too high aspeed, and the pressure pulses produced thereby are of relatively shortduration as compared to pulses produced when the pulley rotates at itsnormal speed (See FIG. 2C), operation of the circuit of the invention issimilar to that described with reference to Condition 4 above. That is,since the P pulses at 54 here are substantially out of phase with the Ppulses at 66, the P pulses which are applied at 64 frequentlyperiodically override the P pulses at 44. Therefore, pressure is appliedfor longer times to the flip-flop 46 output leg 58 than to the flip-flopleg 50. Integrating the pulsed output pressure at 58 by means of thedetector element 7 4) results in a steady state pressure level, which itabove the predetermined threshold level P effects actuation of thedetector '70.

FIG. 3 indicates the manner in which the integrated pressure outputsignal varies with the speed of the sewing machine pulley, and alsoindicates the threshold level P which must be exceeded for actuation ofthe detector 70.

It is to be appreciated that while the curve of FIG. 3 is depicted asbeing generally trough-like, this may be easily change-d, e.g. by somodifying the circuit of FIG. 1 that the integrator 70 connects to theflip-flop 46 .output leg 50 and the operation of the integrator 70 isreversed, where by the FIG. 3 curve will appear inverted.

With respect to the tuning of the circuit of FIG. 1, regardless of thenature or arrangement of the pulley spokes 16, or of the pulse trainproduced thereby, the following procedure prevails: The sewing machineis operated, and while thread 18 is consumed at its normal rate, thedelay device 52 is so adjusted that the integrated pressure level in theflip-flop 46 leg 58 peaks down. At this time, the circuit is properlytuned. For an embodiment employing a pulley as shown in FIG. 1, thiswill be when the obtained pulse delay is substantially as depicted inFIG. 2A.

While the invention has been described in its preferred embodiment it isto be understood that the words which have been used are words ofdescription rather than of limitation and that changes within thepurview of the appended claims may be made without departing from thetrue scope and spirit of the invention.

Having thus set forth the nature of the invention, what is claimedherein is:

1. A modulation control circuit comprising first and second fluidresponsive flip-flop elements, both of which are provided withrespective first and second output members and respective first andsecond control ports, a monostable fluid responsive element having firstand second output members, the first of which is adapted to receivenormally the output fluid of said monostable element, said monostableelement having a control port for switching its output fluid to itssecond output member, means for applying the fluid of said second outputmember of said monostable element to said first control port of saidfirst flip-flop element, means for applying the fluid of said firstoutput member of said monostable element to the first control port ofsaid second flip-flop element, means for applying the output fluid ofsaid first output member of said first flip-flop element to the secondcontrol port of said second flip-flop element, delay means for applyingthe output fluid of said second output member of said second flip-flopelement to the second control port of said first flip-flop element, andmeans responsive to the fluid of the first output member of said secondflip-flop element.

2. The apparatus of claim 1 wherein the first and second flip-flopelements and the monostable element are excited respectively by fluid atfirst, second and third pressures, said first pressure being greaterthan said second pressure, and said second pressure being greater thansaid third pressure.

3. The apparatus of claim 1 including means for applying a train offluid pulses to the control port of said monostable element, and whereinsaid means responsive to the fluid of the first output member of saidsecond flipflop element is adapted to respond to averaged pressures ofthat fluid which are above a predetermined amount.

4. The apparatus of claim 3 wherein said means for applying a train offluid pulses to said control port of said monostable element comprises arotatable spoked wheel and means for so directing a stream .of air atsaid wheel that the spokes thereof modulate said air stream.

5. The apparatus of claim 1 in conjunction with a sewing machine, saidsewing machine being provided with a spoked wheel drivable by the threadthereof as said thread is consumed, means for so directing a stream ofair at said wheel that said stream is modulated by said spokes when saidwheel turns, means for applying the modulated air stream to the controlport of said monostable element, and wherein said means responsive tothe fluid of said first output member of said second flipfiop element ispressure responsive means for alarming when the average pressure of itsreceived fluid exceeds a predetermined amount.

References Cited UNITED STATES PATENTS 3,155,825 11/1964 Boothe2'35--201 3,323,721 6/1967 Topfer et al 1235-201 JORDAN FRANKLIN,Primary Examiner. H. H. HUNTER, Assistant Examiner.

1. A MODULATION CONTROL CIRCUIT COMPRISING FIRST AND SECOND FLUIDRESPONSIVE FLIP-FLOP ELEMENTS, BOTH OF WHICH ARE PROVIDED WITH RESPECTFIRST AND SECOND OUTPUT MEMBERS AND RESPECTIVE FIRST AND SECOND CONTROLPORTS, A MONOSTABLE FLUID RESPONSIVE ELEMENT HAVING FIRST AND SECONDOUTPUT MEMBERS, THE FIRST OF WHICH IS ADAPTED TO RECEIVE NORMALLY THEOUTPUT FLUID OF SAID MONOSTABLE ELEMENT, SAID MONOSTABLE ELEMENT HAVINGA CONTROL PORT FOR SWITCHING ITS OUTPUT FLUID TO ITS SECOND OUTPUTMEMBER, MEANS FOR APPLYING THE FLUID OF SAID SECOND OUTPUT MEMBER OFSAID MONOSTABLE ELEMENT TO SAID FIRST CONTROL PORT OF SAID FIRSTFLIP-FLOP ELEMENT, MEANS FOR APPLYING THE FLUID OF SAID FIRST OUTPUTMEMBER OF SAID MONOSTABLE ELEMENT TO THE FIRST CONTROL PORT OF SAIDSECOND FLIP-FLOP ELEMENT, MEANS FOR APPLYING THE OUTPUT FLUID OF SAIDFIRST OUTPUT MEMBER OF SAID FIRST FLIP-FLOP ELEMENT TO THE SECONDCONTROL PORT OF SAID SECOND FLIP-FLOP ELEMENT, DELAY MEANS FOR APPLYINGTHE OUTPUT FLUID OF SAID SECOND OUTPUT MEMBER OF SAID SECOND FLIP-FLOPELEMENT TO THE SECOND CONTROL PORT OF SAID FIRST FLIP-FLOP ELEMENT, ANDMEANS RESPONSIVE TO THE FLUID OF THE FIRST OUTPUT MEMBER OF SAID SECONDFLIP-FLOP ELEMENT.